The invention pertains to a toolholder for roughing and finishing a workpiece, as well as a method of using the same. More specifically, the invention pertains to a toolholder for roughing and finishing a workpiece, and a method of using the same, which provides an acceptable workpiece surface finish after only one pass of the toolholder relative to the workpiece.
In a typical material removal operation wherein the workpiece and the cutting insert move and rotate relative to each other, there are three basic components. These components comprise the cutting insert, the toolholder that carries the cutting insert, and the workpiece material. Typical material removal operations for which this invention is suitable include turning, threading, drilling, boring, and planing. In some of these types of material removal operations, the toolholder carries one or more cutting inserts in such a fashion that only one type of cutting insert engages the workpiece at any given time.
Although the specific process varies depending upon the workpiece material and the desired end result, many machining operations includes at least two cuts on, or passes relative to, the workpiece. In the typical first (or roughing) cut, a roughing insert engages the workpiece so as to remove a preselected volume of material therefrom so as to achieve a desired dimension and surface finish of the workpiece. After completion of the roughing cut, the roughing insert is either replaced by a finishing insert, or the roughing insert moves out of position and a finishing insert indexes into position, wherein the finishing insert engages the surface of the workpiece which has already been machined by the roughing insert so as to machine the workpiece to a desired final dimension and surface finish.
While the earlier arrangements of toolholders by which the roughing insert and a finishing insert sequentially engage the workpiece achieve satisfactory results, there remains room for improvement. This is especially the case with respect to the operating efficiencies associated with earlier processes in which the roughing insert and the finishing insert sequentially engage the workpiece.
In this regard, it would be desirable to provide a toolholder that carries both a roughing insert and a finishing insert so that the workpiece is roughed and finished in only one cut in contrast to a plurality of cuts. The efficiency of the overall machining process improves upon a decrease in the number of cuts necessary to produce a workpiece with the proper final dimension and final surface finish.